Popping out exhaust

[tory]

My 1978 project is coming along, but do have a couple quirks.
It does have fresh rebuilt carbs, balanced and new points and condenser, new coils wires and plugs.
It does have HD mufflers with no cross over. But are sealed and no leaks.

Popping out exhaust
I have played with timing, and unrelated a second carb rack. But issues stays.
Any advice what to try?

[Fred Camper]

Valve clearance is one issue to check.

[Whiskerfish]

try hooking up a trickle charger when idling. also if you have a IR gun check the header temps to see if that provides any info regarding the different sound.

[tory]

Got some garage time back this weekend. I went through and set all valve adjustments. Still have the popping issue. Checking the left side (which does not pop)
Looks like maybe I should be looking back at carburetors knowing that? If was ignition wouldn't it be both fronts cool?

If it matters, pops frequently cold, much less warmed up. Maybe lean on front right?

[gltriker]

Awhile back, either her or Facebook or...
Someone showed a cool air filter adapter that screwed on the plenum in place of the OW filter housing, that took an aftermarket air filter like a K&N.
Any idea where I can find this?

Carburetors' have already been dynamically engine idle speed synchronized ? Correct?... with a stock GL1000 air filter housing assembly and a Honda GL1000 air filter element?

[tory]

Awhile back, either her or Facebook or...
Someone showed a cool air filter adapter that screwed on the plenum in place of the OW filter housing, that took an aftermarket air filter like a K&N.
Any idea where I can find this?

Carburetors' have already been dynamically engine idle speed synchronized ? Correct?... with a stock GL1000 air filter housing assembly and a Honda GL1000 air filter element?

I never did go that route and the original filter box and correct replacement filter is installed.
And I did balance carbs.

[gltriker]

Awhile back, either her or Facebook or...
Someone showed a cool air filter adapter that screwed on the plenum in place of the OW filter housing, that took an aftermarket air filter like a K&N.
Any idea where I can find this?

Carburetors' have already been dynamically engine idle speed synchronized ? Correct?... with a stock GL1000 air filter housing assembly and a Honda GL1000 air filter element?

I never did go that route and the original filter box and correct replacement filter is installed.

Dynamically synchronized? edit-just found that answer in your last post ; "And I did balance carbs."

[tory]

I'm going to say no, as I have no clue what you mean. I do have a set vacuum gauges and used them to adjust the butterflys and got them all sucking the same vacuum. I don't believe I can be that far off. Maybe?
Bike throttle IS very responsive, starts well. But pops out the right and sounds different. I did try to attach a video but didn't load.

[CYBORG]

I would do a compression test, and /or swap plugs side to side. Almost sounds like a leaking exhaust valve, or an air leak in the exhaust.

[gltriker]

I'm going to say no, as I have no clue what you mean. I do have a set vacuum gauges and used them to adjust the butterflys and got them all sucking the same vacuum.
With the drastic temp difference on front right, I don't believe I can be that far off. Maybe?
Bike throttle IS very responsive, starts well. But pops out the right and sounds different. I did try to attach a video but didn't load.

Good! You synchronized the carburetors on the running engine

Yes, I was successful to download your video and did listen to the exhaust sounds from side to side. You are close.

[tory]

I would do a compression test, and /or swap plugs side to side. Almost sounds like a leaking exhaust valve, or an air leak in the exhaust.

I was pretty confident I did a compression check on this one when I first got it. But I'll be honest, it's been a bit and I'm getting older.....
I've tried to find an exhuast leak but do not seem to have one. They are stock head pipes, new gaskets with 3" nipples welded on, and snug fit slip ons clamped tight. However no cross over.
Seems the popping side (right) sounds best warmed up. But she will idle right down to 500 rpms and responds well to a quick twist.

[cfairweather]

I have a feeling, your #1 carb has a problem but, I am not sure since you tried two carb sets. Let me tell you about a problem that I had recently that sounds similar. I had just rebuilt a 755A set and installed it on my test stand. I have found that this test stand is a must when testing carburetors. My test engine does not have headers so you can see exactly what is happening with each cylinder. When one is too rich, you will see fire coming out of the exhaust port. You can feel the pressure on each one and you can hear a cylinder that is not working like the others. On this particular set, #3 was running too rich at idle, but it had good throttle response and it ran pretty good. I did the common things to resolve the problem, but I just could not get this carb to work correctly at idle. If the idle fuel screw was even 1/4 turn out, it would be too rich and fire would be shooting out. I also had some popping. Eventually, since I had a spare #3 carb, I replaced the carb on the set and that solved the problem. The replacement carb made the engine run much better and it seemed to help the other cylinders perform better. I was able to set the idle fuel screw to 1 3/8 turns without it running too rich. Problem solved. Now back to your problem. Question:
1. When you swapped the carbs out, did you use any components from the original set? For example, did you use the rubber hoses, pilot jets (in the brass elbows), air cut valve, etc from the original set?
2. The problem could be related to clogged slow jet or clogged idle passage on #1.
3. Maybe something related to the air cut system like a leak in the hoses. A leaky air cut hose might cause #1 to run poorly and you would not see a problem on the others at idle.
Good luck.

[redglbx]

Tory, to kind of expand on Cedric’s comments above, my 76 is doing the same thing but popping out of the left bank, been struggling with this for a while now. I have heavily modified 1100 carbs and am beginning to suspect a leaking air cut-off valve diaphragm in one of them.

The 1100 carbs have cut-off valves on each carb, so at this point I’m considering going through and reinstalling the oe carbs which like all 1000 carbs only has the one air cut-off valve on the #1 cylinder. The bike runs extremely well except for the popping.

I Have changed plugs, set & reset the valves, done compression tests and leak down tests multiple times as well as tried all kinds of idle mixture settings and quite frankly nothing has stopped the popping. I have a complete Dyna ignition and was going to replace the module figuring that maybe there was some cross talking going on causing the popping but currently am leaning towards the carbs.

The big problem is that I have severe back issues that limit my ability to walk or be on my feet that has limited my ability to work on things, I put the bike in the shop to work on it back in April and haven’t worked on it or ridden anything since. Supposed to get the back fixed at the end of next month but if I have-a “good” day May get up to the shop, we’ll see.

So Tory, I am assuming you have 1000 carbs that you’re dealing with and suggest that you may want to just change out the air cut-off diaphragm and o’rings in the little module on the front rh side of the plenum box by the #1 carb, they’re are relatively cheap and easy to do. Good luck and let us know.

[gltriker]

Tory, I noted your location is Michigan. I'm sure you would have already been out riding it, wringing out the engine and consuming the gasoline presently in the fuel tank. Rat would advise, fill the tank and ride until you are running low, re-fill the tank and ride some more. Repeat...

[Sidecar Bob]

Why bother with the air cuts anyway? Mike explains why they aren't really needed and how to bypass them here:
https://www.ngwclub.com/forum/viewtopic.php?t=48556